The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Hybrid vehicles having an internal combustion engine as a first source of motive power and an electric motor as a second source of motive power have become increasingly popular based on fuel costs and environmental concerns. In at least one hybrid vehicle, the internal combustion engine is frequently started and stopped to most efficiently operate the vehicle. Some engine starting systems may include retractable pinion electric motors, a pinion synchronizing system, or a belt integrated starter/generator combination. These systems may not be best suited for the frequency of engine starting events associated with a hybrid vehicle. Durability, noise, vibration and harshness (NVH) concerns may exist.
To minimize and/or eliminate NVH issues associated with typical internal combustion engine starting systems, a starter motor gear may be positioned in constant meshed engagement with a rotating member of the internal combustion engine. A clutch is positioned along this power path to allow temporary driving interconnection between the starter motor and the internal combustion engine. While various clutch designs may be incorporated, cost, size, weight, lubrication requirements and torque carrying capacity concerns exist.
At least one known clutch associated with an automotive vehicle is positioned immediately adjacent to or partially within the engine block of the internal combustion engine. This positioning is required because lubricant within the engine block is provided to the clutch as well. While such an arrangement may prove to be beneficial, the positioning of the clutch in this system is limited and is not necessarily desirable. Furthermore, additional special machining may be required to the engine block or other internal combustion engine components in order to provide appropriate passageways for the lubricant to reach and return from the clutch.
Other known clutch characteristics such as the generation of heat and a loss of efficiency when operating in an overrunning mode may not lend themselves for use in a vehicle attempting to maximize energy efficiency. Additionally, some clutches suffer a degradation in performance such as binding when placed in an environment subject to dynamic movement in radial, axial and/or angular directions. As dynamic movement between rotating components increases, some designs become less robust. Internal combustion engine crankshafts may exhibit vibration and dynamic loading during engine operation that may result in torque spiking between internal working components of the clutch. An undesirable oscillatory force may be transferred to other driveline components. Accordingly, it may be desirable to provide an improved internal combustion engine starting system having a robust torque transfer mechanism.